A reduced pressure treatment system (100) comprising: a manifold (104) adapted to be positioned at a tissue site； a regulated chamber in fluid communication with the tissue site to deliver a desired therapy pressure to the tissue site； a charging chamber adapted to store a charging pressure that is less than the desired therapy pressure； a passage providing fluid communication between the regulated chamber and the charging chamber； a valve body operably associated with the passage to substantially reduce fluid communication through the passage when a pressure in the regulated chamber is less than or equal to the desired therapy pressure and to allow fluid communication through the passage when the pressure in the regulated chamber exceeds the desired therapy pressure.
